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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    
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<script>
    let arr = [23,566,21,542,78];
    console.log(arr[2]); //21
    let arr2 = ['tom',34.4,true,,,,];
    console.log(arr2[4]);
    arr2[4] = null;
    console.log(arr2[4]);
    console.log('-----------');
    //遍历数组
    console.log(arr.length);//获取数组长度
    for(let i = 0;i<arr.length;i++){
        console.log(arr[i]);
    }
    //1.找出数组score中的最大值，并算出这个数组的平均数
    //score= [89,67,59,90,54,77,83,88.5,43,10,68]
    console.log('------------------------');
    let score = [89,67,59,90,54,77,83,88.5,43,10,68];
    let max=score[0];
    let sum=0;
    for(let i=0;i<score.length;i++){
        if(score[i]>max){
            max=score[i];
        }
        sum = sum + score[i];
    }
    console.log(max);
    console.log(+sum/score.length);
</script>
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